NO166844B - PROCEDURE FOR THE EXCESSION OF AN EXTENDABLE CHARGE IN THE GAS PHASE AND REACTOR FOR IMPLEMENTATION OF THE PROCEDURE. - Google Patents

Description

The present invention relates to a method for oxidizing an oxidizable charge in gas phase with a mixture of gas containing at least one oxidizing gas, and a reactor for carrying out this method.

It applies more particularly to a slow and partial oxidation of oxidizable charges such as hydrocarbons, with a view to the production of synthesis gas comprising essentially carbon monoxide and hydrogen, for the synthesis of, for example, methanol and higher alcohol homologues. It can also, for example, apply to the oxidation of effluents from the conversion of steam, benzene, or to ammonoxidation reactions.

Although the oxidizing gases may in particular be oxygen, ozone or halogens, only reactions with oxygen are used in the example.

It is known to carry out a partial oxidation of methane, as stated, for example, in US patent 2,621,117.

The reaction takes place in a flame, where the mixture of the gas is never perfect. Under these conditions, high temperatures are quickly reached in the zones that are rich in oxygen.

The gas that is produced at a high temperature is then mixed in a zone that is rich in a charge to be oxidized and promotes cracking of the molecules with the formation of carbon which, for example, tends to contaminate the catalysts in the rest of the process and thus reduce the yield of the reaction .

In the case of methane, a production of carbon is observed and the synthesis gas must later be purified before its use, for example for the synthesis of methanol starting from carbon monoxide and hydrogen.

In addition to the formation of black smoke, excessive overheating can occur in the zone where the contact between the reaction gases is carried out and in a large number of cases, these undesirable effects can be returned to the mixing device for the reaction gases at the inlet to the reactor, as the mixing of gas is carried out at a speed which is too slow compared to the reaction rate in the gas phase.

This is the case when the oxygen is introduced through a single channel which otherwise should have a sufficient cross-section to admit the entire amount and, although the gas is injected at high speed through this cross-section, the dispersion rate of the oxygen molecules is slow, compared to the reaction rate. Furthermore! is the jet of oxygen in the area where it leaves this opening, generally in the area of the gas to be oxidized and which circulates at low speed in the reactor, which is not advantageous for a rapid dispersion of the oxygen molecules.

EPO patent 1946 describes a reactor where the oxygen, under the assumption of a large amount, is injected into the process gas by means of a series of parallel channels, each of these channels ending with an outlet opening of which at least one has a very reduced size, such as a gap whose width is preferably less than 8 mm.

In order to increase the dispersion rate of the oxygen in the process gas, this is therefore given a strong spiral-shaped movement around these channels, achieved by a tangential injection of this gas against the inner walls of the apparatus.

US patents 4,381,187 and 3,741,533 also illustrate the state of the art in the area.

Incidentally, it is well known, especially from the book by G. de Soete and A. Feugier: "Aspects physiques et chimique de la combustion" Editions Technip, pages 87 to 93, to use this wall effect to reduce the reaction rate and avoid propagation of the flame.

In the present case, the presence of pure oxygen and high temperature implies a high heat flow which necessitates devices to stop the flame, so that the reaction can take place without explosion, although one is within the explosion limits (especially when it comes to partial oxidation of methane).

The objectives which are proposed to be achieved and which provide answers to the problems emphasized in prior art are essentially the following: - a distribution of oxygen and of charge which is suitable for achieving a quasi-homogeneous mixture/, under full control" between the oxygen and the charge to be oxidized. This distribution should be particularly suitable for fast. dispersion of the oxygen molecules. - a "stopping or retarding of the flame", whereby explosions are avoided and it is nevertheless made possible to work at temperatures that can reach over 1000°C, with a view to protecting the reactor and the mixing device against excessive heat emitted during the partial oxidation.

The present invention proposes a new method whereby the disadvantages of the previously known technique are avoided. It applies more particularly to a method for the oxidation of an oxidizable charge in gas phase with a gas mixture containing at least one oxidizing gas, according to which the following steps are carried out in sequence: a) the oxidizable charge and the oxidizing gas are circulated simultaneously in a distribution zone of ceramic material, comprising at least one row of channels of a first type, so that one of the two gases which make up the oxidizable charge and the oxidizing gas, respectively, circulates separately in the interior of said row, while the other of the two gases circulates separately outside this row, in that the oxidizable charge and the oxidizing gas at least in a part of the mentioned zone flow through a number of spaces representing passages and which have a dimension in at least one direction that is at most equal to 10 mm, corresponding to the length of the reducing part of the flame formed by oxidation of the aforementioned charge with the oxidizing gas,

b) then the oxidizable gas and the oxidizing gas distributed in this way are mixed in a mixing zone of

ceramic material forming a number of spaces representing passages having, at least in one direction, a dimension comparable to the dimension of the passages in step a) and

c) the mixture of the products from step b) is reacted in a reaction zone of ceramic material, comprising a number of rooms

which represent passages and which, at least in one direction, have a dimension comparable to the dimension of the passages defined in steps a) and

b), as the distance between the distribution zone and the mixing zone, firstly, and between the mixing zone and the reaction zone, secondly, is at least equal to the length of the reducing part of the flame.

The channels in the mentioned row can be close to each other. The outer side of the said row may, according to one embodiment, comprise a first ceramic cladding which may comprise either at least one row of channels of a second type, or particulate elements.

According to these two embodiments, one of the two gases (e.g. the oxidizable charge) circulates through the channels of the first type, while the other gas (e.g. the oxidizing gas) circulates through the cladding.

The surfaces vis-a-vis the mixing zone and the distribution zone, firstly, and the surface vis-a-vis the mixing zone and the reaction zone, secondly, are advantageously dimensioned so that the surface of the mixing zone is at least equal to the surface of the distribution zone and at most equal to the surface of the reaction zone.

The dimension for the aforementioned passages, which advantageously corresponds to the retardation length for the flame, is at most equal to 5 mm and preferably between approx. 0.1 to 2 mm.

The distribution zone, the mixing zone and the reaction zone are advantageously made of refractory ceramic material, which can be selected from the group consisting of mullite, cordierite, silicon nitrides such as Si3N4, alkaline earth oxides, transfer metal oxides and silicon carbide.

The present method leads to improved yields, for example of synthesis gas, compared to known methods.

The invention also applies to a reactor for the oxidation of an oxidizable charge in gas phase with a gas mixture containing at least one oxidizing gas. The reactor includes means for supplying oxidizing gas, means for supplying oxidizable charge and means for exhausting the reaction products.

It is also characterized by comprising in combination, on at least part of its cross-section, distribution means of ceramic material consisting of at least one row of at least one channel of a first type connected to supply means for one of the two gases ( oxidizable charge or oxidizing gas) and in whose interior the said gas circulates, the said distribution means comprising a first filling connected with supply means for the second of the two gases outside the said channel, the interior of the said channel is also filled with a second filling, the said fillings being adapted so that they define, at least in part of the distribution means, a number of spaces having passages which, at least along one direction, have a dimension at most equal to 10 mm, the said area and the said first filling is particularly adapted to distribute divided streams of the oxidizable charge and the oxidizing gas in a mixing member of ceramic material through their end so m is closest to the said mixing device, the mixing device being adapted to mix the said charge and the said oxidizing gas and to define along the entire mixing device a number of spaces representing passages which, according to at least one direction, have a dimension that is at most equal to 10 mm, the said mixing member being located at a distance which is at most equal to 10 mm firstly from the end of the said row of channels and the said first filling and secondly from a reaction member of ceramic material, comprising the said second filling of ceramic material which is adapted to define at least in a part of the reaction body a number of spaces representing passages which, along at least one direction, have a dimension of no more than 10 mm, thanks to which the reaction products are channeled towards the said discharge means .

With the expression "in at least one part" of the distribution or reaction means, is meant at least in the immediate vicinity of the mixing means, next to the distribution means and next to the reaction means.

According to a first embodiment, the mixing member comprises many layers of meshes which are significantly offset in relation to each other and filled with the aforementioned second filling of ceramic material.

According to a second embodiment, the mixing device comprises many plates, preferably essentially vertical, each of which comprises a number of protrusions and channelings that lean towards each plate, the plates being arranged so that the protrusions and channelings cross each other.

To facilitate understanding, the embodiment example in the description describes a reactor where the distribution means advantageously comprise a monolith with several channels close to each other comprising at least one row of at least one channel of the first type which is connected to the supply means for the oxidizable charge, this row alternating with a row of at least one channel of the second type which is connected to the supply means for oxidizing gas, each channel being filled with a filling which is adapted to define said plurality of spaces.

Preferably, the first row and the last row are reserved for the oxidizable charge.

The above dimensions and the distance from the mixing device to the outlet end for the distribution means and the distance from the mixing device to the inlet for the reaction device or the reaction zone are advantageously at most equal to 5 mm and preferably between 0.1 and 2 mm.

According to one embodiment, the spaces are defined by ceramic fillings which can comprise at least one monolith consisting of many closely adjacent channels, which advantageously lie essentially parallel to each other, each of the channels having a cross-section between 0.0025 and lOO mm<2> .

Preferably, the channels in the distribution monolith or those in the reaction zone monolith have a cross section that lies between. 0.01 and 25 mm<2>. This cross-section can have any shape, but is preferably polygonal and most preferably square or rectangular.

When the mixing device comprises many layers with meshes that are offset relative to each other, the channels in the monolith which are placed in the meshes in the mixing device have a cross-section that is preferably between 0.01 and 25 mm<2.> Similarly, the cross-section of the channels in the mixing device, when the plates are arranged substantially in the direction of gas flow, measured when the plates that are close to each other are compatible with the retardation length of the flame and consequently lie between 0.0025 and 100 mm<2> and preferably between 0.01 and 25 mm<2 >.

This cross-section in the channels can have any shape, for example polygonal and is preferably square or rectangular.

The channels generally have a varying slope and the degree of slope can vary from a few degrees in relation to the vertical to a few degrees in relation to the horizontal. Preferably it is between 30 and 50 degrees.

The plates generally have a small thickness to improve mixing. They are generally close to each other, but they may optionally be spaced up to the level of the interior of the crossed channels, and remain consistent with the braking length.

The rooms can also be defined, according to another embodiment of fillings comprising particulate elements such as balls and ceramic rods.

In a particularly advantageous embodiment, the monoliths are not empty, but at least one of them may comprise at least one filling with elements such as e.g. balls and rods of ceramic, with dimensions substantially smaller than the dimensions of a single channel, these materials being held at the level of different zones by grids of ceramic material.

In general, the charge and the oxidizing gas circulate through the fillings and/or the filling in the direction of the mixing zone.

The three zones that make up the reactor according to the invention, and in particular the distribution zone with at least one row of at least one channel, can be filled with particulate elements described above, but it is only conceivable to fill one of the three zones, in whole or in part, if the dimension of each single channel in a specific zone is otherwise compatible with the retardation length for the flame.

For example, only the monolith in the reaction zone can be filled with spheres or also the latter and the monolith in the distribution zone.

The size of these particles is generally between 0.01 and 10 mm.

The fillings can likewise, according to yet another embodiment, be only a catalyst or combined with the above-mentioned filling. The catalyst can e.g. be copper chloride or potassium chloride deposited on aluminum oxide, vanadium oxide deposited on aluminum oxide or with the addition of potassium sulfate deposited on silicon dioxide, cerium or lanthanum deposited on silicon dioxide, bismuth phosphomolybdate or cobalt molybdate deposited on silicon dioxide, metal oxides (eg Ag and Cu) and porous silicon carbide covered with silver.

The above-mentioned fillings and the filling make it possible to reduce the length of the reducing part of the flame to a value that is difficult to achieve with the help of known technology, without risking bad effects and, consequently, to carry out the oxidation reactions in the presence of pure oxygen.

In the distribution zone, the oxidizing gas flows through the rows of channels of the first type, for example of the order of magnitude n-2, n, n+1, n+3, n+5, where n is any whole number.

Rows of channels ...n-2, n-1, n+2, n+3, n+6, n+7... can also be placed for the charge and rows ...n, n+1, n+4, n+5, n+8, n+9 for the oxidizing gas.

The fluid chosen for the first row matters little, it is generally interesting to take account of shifting and preferably, that a row of channels reserved for oxidizing gas lies between the rows reserved for the charge when, for example, it concerns a monolith in the distribution zone. This gives the advantage that all

oxidizing gas is consumed.

The distribution zone with several channels offers the advantage that. the oxidizable charge and the oxidizing gas flow in the form of even plugs and avoid return of the flame provided that the oxidation reaction is injected by mixing the fluids that introduce heat into the reactor.

The mixing device is advantageously placed in a plane which is essentially perpendicular to the gas flow, but it can be oriented differently.

A high number N of mixing layers caused, for example, by the presence of N discs of small thickness, of meshes that are offset or decentered, with any polygonal cross-section, but advantageously square or rectangular,

shares the current. The mixing zone therefore makes it possible to achieve a quasi-homogeneous micro-mixture under perfect control where the oxygen is, for example, quickly dispersed, and an oxidation reaction where the propagation of the flame is stopped, thereby avoiding the risk of explosion.

Finally, the actual reaction zone allows the oxidation reaction to take place under control of the heat level that is achieved and for the reaction products to be exhausted.

Due to the small cross-section of the channels and meshes

in the different layers where the channeling of the mixing device and likewise due to the distance between the different agents that are combined in the reactor, a new method and reactor for oxidation is finally achieved where no back-mixing takes place, or explosions (or return of flame) .

As the entire device is made of refractory material (ceramics), is

the use of the neutral vis-a-vis charge, the oxidizing gas and the reaction products. It can function at wall temperatures that reach 1,200 to 1,500°C.

The channels in the monolith have a unit cross-section which lies

between 0.0025 and 100 mm<2> and are preferably essentially the same. They can advantageously occupy the entire surface of the reactor and have, for example, a cylindrical shape when the reactor is tubular, but the monlits can also have a square, rectangular or any other cross-section.

The length of each individual channel can be, for example, from 10 to

3000 mm.

The number of layers of disks that divide the gas flow of the oxidizable charge and the oxidizing gas can for example be between 6 and 50 and preferably between 20 and 40. The thickness of each unit varies from 1 to 10 mm and is preferably equal to 5 mm.

Particularly interesting results are achieved without, for example, deposition of coke and with a maximum yield when the surfaces directly opposite the mixing zone and the distribution zone and the surfaces directly opposite the mixing zone and the reaction zone are essentially the same.

The arrival of the oxidizable charge in the rows of the first

type of channels that will distribute it in the distribution zone takes place essentially perpendicular to the axis of these rows, at a midpoint located at a distance from the mixing zone that is between 40 and 95% of the total length of the distribution zone.

In contrast, the intake of oxidizing gas i

the rows of the second type of channels (first filling) that should

distributing it in the distribution zone is carried out along the axis of these channels.

It is also possible to reverse the intakes of the gaseous fluids, e.g. the oxidizable charge can be introduced along the channel axis, while the oxidizing gas can be introduced essentially vertically as in the case described above.

One of the following channel cross-section shapes can be selected: square, rectangular, cylindrical, elliptical, circular or triangular.

The oxidizable charge and the oxidizing gas circulate essentially in the same direction towards the mixing zone, e.g. from the bottom up or from the top down when the reactor is shaped like a pipe that stands vertically.

The oxidisable charge that can be used according to the invention comprises, for example, saturated, aliphatic hydrocarbons, such as e.g. methane and the effluents from the conversion process in vapor form, orthoxylene, naphthalene, benzene, methanol, the methane-toluene mixture and the ethylene-hydrochloric acid mixture.

The invention will be better understood with the help of the description of some embodiments, which shall only illustrate and not limit, as can be done below with the help of the accompanying figures: Figure 1 schematically represents an embodiment of the method according to the invention by means of a

longitudinal section,

Figures 2A and 2B illustrate different embodiments of the distribution zone for the oxidizable charge and the

the oxidizing gas,

Figures 3A, 3B, 3C and 3D show slices of the mixer

according to three different embodiments seen from above, figure 4 illustrates a mixing means of plates,

Figure 5 schematically represents another monolith from

the reaction zone and

figures 6 and 7 show two other embodiments according to the invention.

Figure 1 shows, according to one embodiment, a vertical, cylindrical oxidation reactor 1 with an elongated shape comprising a filling consisting of a first monolith 2 with a cylindrical shape, but whose useful cross-section is, for example, square, in which channels 7 of silicon carbide are arranged, which are essentially parallel to each other and to the reactor axis and a mixer 3, for example of mullite consisting of a number of disks 8a, 8b, 8c... with cylindrical shape, small thickness and staggered meshes 9.

Below this mixer is shown a second monolith 4, with a cylindrical shape, but with a useful cross-section similar to that of monolith 2, which represents the reaction zone (fig. 5) of mullite and comprising a series of closely spaced channels 10, which are essentially parallel to each other and to the reactor axis. The individual cross-section in each channel 10, as in each channel 7, for example with a square shape, is approx. 1 mm<2> and their length is, for example, around 50 cm.

The channels 10 must firstly channel the reaction products to an exhaust line 13 and secondly, due to their small width and the wall effect, and "slow down the flame", which enables the reaction to take place without an explosion.

In this embodiment, the oxidizable charge, which is preheated to around 400°C, enters through a line 5 and is fed from top to bottom in many rows 11 of a first type of channels 7a (Fig. 2A).

The charge is distributed in this way in the form of even currents which are essentially parallel to each other and to the axis of the reactor 1.

The oxidizing gas which is, for example, preheated to 150°C is likewise distributed in the form of steady streams which are essentially parallel to each other and to the axis of the reactor 1 and circulates from top to bottom in the rows 12 to the channels 7b of the second type which are arranged alternating with rows 11 in channels 7a.

The upper end of the channels 7b is sealed with a paste of ceramic material. The supply of gas from these rows 12 is carried out, for example, by following a direction which is essentially perpendicular to the axis of these channels 7b, thanks to a supply line 6, and a middle point on at least one generatrix of the reactor which is located at a distance from the mixing zone 3 that is between 40 and 95% of the total length of the first monolith 2.

In order to reach the rows 12 (fig. 2A), the monolith 2 is cut on two opposite sides, in the axis of the supply line 6 for oxidizing gas (not shown in the figure), to reach the rows 12 vertically before the gas is distributed.

The walls as on. this way is made visible, is pierced by slits, so that the channels 7b are released and the entire depth of each row 12 to allow the passage of oxidizing gas.

With the help of a ceramic paste, the unnecessary channels are closed at the level of the cutout, which serve neither for the passage of oxidizing gas nor for oxidizable charge.

If the first monolith 2 does not have a square cross-section, the channels are sealed again, for example by means of a ceramic paste around the edges at the outer wall of the reactor, but in contrast, if according to another embodiment they occupy the entire surface of the reactor as shown in fig. 2B, it is only possible to hollow out the wall of the reactor at the level of the rows 12 which are intended for distribution of the oxidizing gas, and connect these latter with the line 6 for intake of gas.

The width of the gap produced in this way is at most equal to the width of each row 12. The width of each row can correspond to the width of one, two or three channels depending on the dimensions of the meshes in the mixer.

The streams of oxidizing gas and oxidizable charge alternate and are brought into contact in the mixer 3.

The oxidation reaction is initiated at this stage, all the more so as the fluids are preheated. In order to avoid any entrainment of the reaction, and as a result any explosion, the cross-section in each individual channel is not arbitrary, but equal to a value between 0.0025 and 100 mm<2> and corresponds to the length of the reducing part of the flame.

Likewise, the cross-section of each mesh or channel in the monolith 9 at the level of each disk 2 in the mixer 3 should be such that it corresponds to a dimension that is at most equal to the length of the reducing part of the flame. Finally, the distance between the first monolith and the mixer is at most equal to 10 mm, a distance which is also found for the same reasons between the mixer 3 and the second monolith 4.

Advantageously, the surfaces vis-a-vis the mixing zone and the distribution zone for the first and the surfaces vis-a-vis the mixing zone and the reaction zone for the second are essentially the same.

These surfaces are determined by a plane that is perpendicular to the direction of flow or to the channels.

They are preferably substantially equal to the cross-section of the reactor in a radial plane, so that any surface in the reactor is used at full capacity (Fig. 2B).

Figures 3A, 3B, 3C and 3D represent different embodiments of the mixer 3. This actually comprises a number of cylindrical disks 8a, 8b, 8c with a diameter that is preferably equal to the diameter of the reactor, and a thickness that is between 1 and 10 mm. Each disk 8 is equipped with a network of channels (monolithic) with an individual cross-section that lies between 0.0025 and 100 mm<2> and that corresponds to the surface of a square where at least one of the dimensions is equal to the length of the reducing part of the flame.

The mesh in each disc is shifted in the x and y directions in the plane, preferably by a if a is the side of a square.

2

The discs are stacked up and held in place, for example, by a beret which is not shown in the figure, and which is placed in a slot 14 which is made for this purpose. It thus ends in a migration of fluid flows shown in figure 3D, which enables a homogeneous mixture where the risk of propagation and explosion during the oxidation reaction is completely avoided.

According to another form of method which is represented by figure 3B, the discs 8a, 8b, for example with a square cross-section when the monolith 2 has a square cross-section, can be arranged alternately so that one of the discs has the meshes or channels oriented diagonally to the other, etc.

The stacking of the disks can, for example, advantageously be carried out with an alternation of 45° with mesh size a for one disk and a mesh size b = a\/ 2 for the other arranged in

2

45°.

The channels according to Figure 3C can also be round and the channels in a disc can for example be offset according to a single plane axis or according to the two axes (Fig. 3C).

Figure 4 shows another example of the design of the mixing device. It comprises a number of plates 21 which are placed generally according to the gas flow and advantageously vertically and parallel to the axis of the channels 7a.

Each plate, whose dimensions are, for example, 200 x 50 x 3 mm, is hollowed out from both edges of the channelings 23 to approximately 1 mm in width and 1 mm in depth.

The protrusions 22 which are determined in this way have essentially the same dimensions. The channelizations 23 have an inclination of approximately 45° in relation to the axis of the reactor or to the fluid flow on one of their phases and substantially at the same angle, but in an opposite direction on the other side. They can be closely adjacent to each other, so that the sides in contact with two adjacent plates exhibit crossed channels, which favors efficient mixing of the fluids.

In the example shown in Figure 4, however, two plates have been removed to better illustrate the crossing of the channels 23. At the outlet of the mixer, the oxidation reaction of the gas mixture continues in the reaction zone which is represented by the second monolith 4 described above and which is at a distance of no more than 10 mm from the mixer 3 to avoid any risk of propagation of the reaction.

The described assembly of the means or organs 2, 3, 4 is held in a sleeve 15, for example of mullite, and is inserted into a tube ring 16 of steel covered with refractory concrete 18 according to a known technique. The connections 17 of refractory fibers are placed on both sides of the cavity and make it possible to isolate the oxidizable charge and the oxidizing gas.

The achievement of tightness in the tight connections between the monolith and the metal ring covered with refractory concrete is an interesting technique because it avoids connections between ceramic and metallic conductors which, due to thermal stresses during heating or cooling, cause breakage in the ceramic material.

This technique also makes it possible to connect several monoliths without having to use an adhesive between the monoliths or a ceramic-ceramic connection with flanges whereby tightness is achieved by screwing the flanges.

When it comes to oxidation reactions under pressure and stoichiometries that necessitate very small retardation lengths for the flame, which is difficult to carry out on the technological level, it is possible according to another method shown in figure 6, to fill the reactor 1 at least partially, for example the mixing zone and in particular the reaction zone 4, with ceramic balls 19 or with any other forms of filler bodies including, for example, ceramic rods, with dimensions which are chosen as a function of the length of the reducing part of the flame, and which are retained by a grid 20 or a catalyst.

According to another embodiment of the distribution zone illustrated in figure 7, the reactor can comprise at least one row 11 consisting of at least one channel 7a and connected to the supply means 5 and around the entire row 11 a filling 12a connected to the supply means 6 and comprising particulate elements with a size between 0, 01 and 10 mm which provide room if the passenger has a dimension at most equal to 10 mm.

A grid 20 retains the particulate elements

in the reactor. The rows 11 of channels are filled with particulate elements 25 if the dimensions of the channels are not compatible with the length of the reducing part of the flame.

The connections 17 of refractory fibers which are placed between each row 11 make it possible to isolate the oxidizable charge from the oxidizing gas and can be easily removed for filling or emptying the filling bodies.

Thanks to these layouts and the materials used, it has been achieved to carry out oxidation reactions at very high temperatures of, for example, 1,300°C, without adverse deposition of carbon and with residence times in the reactor that do not exceed, for example, 1,000 ms, while at the same time protecting the reactor from the the heat given off during the reaction.

The following example shall illustrate the invention:

EXAMPLE:

A vertical reactor 1 is made with a tubular shape comprising:

a first monolith 2 of silicon carbide with a length of 170 mm,

round cross-section (diameter =40 mm) and whose cross-section for each channel is 0.64 mm<2> (thickness for a partition is 0.1 mm).

On one of the sides of the monolith representing the upper part, a part of the channels is sealed with a ceramic paste to obtain a square with a side of 26 mm. In this square, two channel rows out of four are alternatively sealed.

Next, 30 mm of the monolith 2 is hollowed out from the side 60 mm taken from the mixer 3, on two opposite sides in the axis for the inlet line for oxygen provided that this is used as oxidizing gas. The depth of the recess is 7 mm in the middle, so that it is perpendicular to the square defined above.

Cracks are created in the walls that thus appear*, the location of which corresponds to the dense rows of channels on the upper side of the monolith. The oxidizable charge and the oxygen are made to flow under a pressure of 10 bar.

The channels that are freed up due to the hollowing out are also sealed to prevent the oxygen from entering the reactor through these channels.■

a mixer 3 with the same surface as the monolith 2 formed by .

monoliths of mullite of the same size as above, having a cross-section of 0.64 mm<2>, 5 mm thickness and glued to the first monolith. It alternates as described above with 20

monoliths whose center corresponds to the intersection of two channel walls and 20 monoliths whose center corresponds to med

center in a canal.

- a second monolith 4 of mullite whose cross-section in each channel is 0.64 mm<2>, with a length of 450 mm and the same surface as the mixer 3. This monolith is in contact with the mixer. The entire reactor 2,3,4 is held by a sleeve of mullite with

635 mm length.

In the reactor as described above and which operates below 10 bar, an oxidizable charge comprising a gas mixture at 400°C and whose composition is as follows is introduced through the upper line 5: ^n:::". «—— 940OC-<p >the roaukt has the following composition:

Claims (17)

1. Method for flame oxidation of an oxidizable charge in gas phase with a gas mixture, containing at least one oxidizing gas, characterized by the following successive steps: a) the oxidizable charge and the oxidizing gas are circulated simultaneously in a distribution zone of ceramic material, comprising at least one row of channels of a first type, so that one of the two gases which make up the oxidizable charge and the oxidizing gas, respectively, circulates separately in the interior of said row, while the other of the two gases circulates separately outside this row , the oxidizable charge and the oxidizing gas flowing at least in part of the said zone through a number of spaces representing passages and having a dimension in at least one direction that is at most equal to 10 mm, corresponding to the length of the reducing part of the flame which is formed by oxidation of the said charge with the oxidizing gas, b) then the oxidizable gas and the oxidizing gas which are distributed in this way are mixed in a mixing zone of ceramic material which forms a number of rooms representing passages which have at least in one direction a dimension comparable to the dimension of the passages in steps a) and c) the mixture of the products from step b) is reacted in a reaction zone of ceramic material, comprising a number of rooms representing passages and which, at least in one direction, have a dimension comparable to the dimension of the passages defined in steps a) and b), the distance between the distribution zone and the mixing zone for the first and between the mixing zone and the reaction zone second, is at least equal to the length of the reducing part of the flame. 2. Method according to claim 1, characterized in that the second gas is circulated outside the said row through a first filling. 3. Method according to claim 2, characterized in that the supply of the oxidizable charge in the rows with the first type of channels which are to distribute it in the distribution zone is carried out in a direction which is essentially perpendicular to the axis in a middle point located at a distance from the mixing zone which lies between 40 and 95% of the total length of the distribution zone and that the supply of oxidizing gas in the aforementioned filling which is to distribute it in the distribution zone is carried out along the axis of the aforementioned rows. 4. Method according to claim 2, characterized in that the supply of the oxidizable charge in the rows of the first type of channels which are to distribute it in the distribution zone is carried out along the axis of the said rows and that the supply of oxidising gas in the said filling which is to distribute it in the distribution zone is carried out in a direction which is essentially perpendicular to the axis of the said channels of the first type in a middle point located at a distance from the mixing zone which is between 40 and 95% of the total length of the distribution zone. 5. Method according to any one of claims 1 to 4, characterized in that the oxidizing gas is oxygen. 6. Oxidation reactor for carrying out the method according to claim 1, comprising means for supplying oxidizing gas (6), means for supplying oxidizable charge (5) and means for exhausting reaction products (13), characterized in that it at least over a part of its cross-section comprises distribution means (2) of ceramic material, consisting of at least one row (11) of at least one channel of a first type (7, 7a) connected to supply means (5) for one of the two gases (oxidizable charge or oxidizing gas) and in the interior of which the said gas circulates, the said distribution means comprising a first filling (12a) connected to supply means (6) for the second of the two gases outside the said channel, the interior of the said the channel is also filled with a second filling (25), the said fillings (12a, 25) being adapted so that they define, at least in part of the distribution means, a number of rooms that have passages that at least along one direction, has a dimension i which is at most equal to 10 mm, said area (11) and said first filling (12a) are particularly adapted to distribute divided flows of the oxidizable charge and the oxidizing gas in a mixing means (3) of ceramic material through their end which is closest to the said mixing device, the mixing device being adapted to mix the said charge and the said oxidizing gas and to define along the entire mixing device (3) a number of spaces representing passages which, according to at least one direction, have a dimension that is at most equal to 10 mm, the said mixing means (3) being located at a distance which is at most equal to 10 mm firstly from the end of the said row (11) of channels and the said first filling (12a) and secondly from a reaction means (4) of ceramic material, comprising said second filling of ceramic material which is adapted to delimit at least in part of the reaction body a the number of spaces representing passages along at least one direction, having a dimension of no more than 10 mm, thanks to which the reaction products are channeled towards the said draining means (13). 7. Reactor according to claim 6, characterized in that the mixing member (3) comprises a number of layers (8a, 8b, 8c...) of meshes which are significantly offset in relation to each other and filled with the aforementioned second filling of ceramic material. 8. Reactor according to claim 7, characterized in that the mixing device (3) comprises a number of essentially vertical plates (21) each of which has a number of protrusions (22) and channels (23) which lean in the opposite direction of each plate, the said plates being placed so that the projections (22) and the channels (23) are crossed. 9. Reactor according to any one of claims 6 to 8, characterized in that the mixing member (3) has, in section on a plane that is perpendicular to the direction of flow in the channel (7a), a surface that is at least equal to the surface in the distribution member (2) and at most equal to the surface in the reaction member (4). 10. Reactor according to any one of claims 6 to 8, characterized in that the mixing member (3) has, in section on a plane perpendicular to the direction of flow in the channel (7a), a surface which is substantially equal vis-a-vis the surface in the distribution member (2) and vis-a-vis the surface in the reaction member ( 4) • 11. Reactor according to any one of claims 6-10, characterized in that the supply means (5) for oxidizable charge are connected to channels of the first type (7a) at an intermediate point located on at least one of the generators for the reactor on a distance from the mixing device (3) that lies between 40 and 95% of the total length of the distribution device (2) and in that the supply means for oxidizing gas (5) are connected to the first filling (12a) at a point opposite the nearest end of the mixing device ( 3). 12. Reactor according to any one of claims 6 to 10, characterized in that the supply means (5) for oxidizable charge are connected to channels of the first type (7a) at a point opposite the nearest end of the mixing member (3) and that the supply means for oxidizing gas (6) are connected to the first filling (12a) ) in an intermediate point located on at least one of the generators of the reactor, at a distance from the mixing device which lies between 40 and 95% of the total length of the distribution device. 13. Reactor according to any one of claims 6 to 12, characterized in that the first and second fillings (12a, 25) comprise at least one monolith (2 or 4) which consists of a number of closely spaced channels. 14. Reactor according to claim 13, characterized in that at least the monoliths (2 or 4) also comprise at least one filling of elements such as ceramic balls and rods. 15. Reactor according to any one of claims 6 to 14, characterized in that the fillings comprise a catalyst. 16. Reactor according to any one of claims 6 to 15, characterized in that at least one of the bodies (2, 3, 4) comprises at least partially a filling of elements such as ceramic balls and rods. 17. Use of a reactor according to any one of claims 6 to 16, in particular for the synthesis of methanol and higher alcohol homologues starting from carbon oxides and hydrogen.